Question

A runner weighs 560 N (about 130 lb), and 74% of this weight is water.

(a) How many moles of water are in the runner's body?
moles

(b) How many water molecules (H2O) are there?
molecules

Answer 1

runner's mass = 560N/g = 560/9.8 kg
weight of water =(560/9.8)*74% kg
=(560/9.8)*.74*1000 g
atomic mass of hydrogen=1g/mol
atomic mass of oxygen=16g/mol, so
atomic mass of water=2x1+16=18g/mol
moles water=(560/9.8)*.74/18
molecules=[moles water]*6x10^23